In a cabinet (rack) in which electronic apparatuses such as server apparatuses are accommodated (installed), cooling fans are often provided to cool the electronic apparatuses by exhausting heat generated by the electronic apparatuses externally from the inside of the rack. FIG. 1 depicts a server rack 100 of related art. In the example depicted in FIG. 1, a plurality of cooling fans 102 are arranged in the height direction of a back door 101 of a server rack 100. The server rack 100 depicted in FIG. 1 uses a front intake/back exhaust system that takes in air from the front of the rack and exhausts the air from the back by rotating the cooling fans 102. Other than this system, there are a front intake/top exhaust system that takes in air from the front of the rack and exhausts the air from the top of the rack, a bottom intake/top exhaust system that takes in air from the bottom of the rack and exhausts the air from the top of the rack, and so on.
Recently, suppression of the power consumption of cooling fans is increasingly requested. In response to such a situation, a cooling technique has been proposed in which a plurality of cooling fan units are detachable and the number of revolutions of cooling fans is controlled depending on the number of cooling fan units that operate normally.
Japanese Laid-open Patent Publication No. 2005-159281, Japanese Laid-open Patent Publication No. 5-243768, Japanese Laid-open Patent Publication No. 2008-123200, and Japanese Laid-open Patent Publication No. 2011-66366 are examples of related art.
If the ratio of accommodation (installation) of electronic apparatuses in a cabinet is low, the cooling fans corresponding to the portion (vacant space) in which no electronic apparatuses are accommodated may not be necessarily operated.
In addition, the state of installation of electronic apparatuses in the cabinet may be changed when, for example, the user adds an electronic apparatus. The amount of heat generation of electronic apparatuses accommodated in the cabinet is not fixed and may vary depending on the type and operational status of the electronic apparatuses.